Congenital heart disease (CHD) refers to the various malformations of the heart and surrounding vessels that occur prior to birth. Almost 1% of children are born with some form of significant CHD. CHD remains a leading cause of infant death in the United States. Many infants with CHD develop exuberant blood flow to their lungs that, if left untreated, may result in overwhelming congestive heart failure and death. For example, in ventricular septal defect (VSD), the most common type of CHD occurring in about 37% of cases, holes in the septum allows oxygen rich blood entering into the left ventricle from the lungs to leak out to the right ventricle and escape out the pulmonary artery instead of out the aorta and to the rest of the body. When, however, complete surgical repair in infancy is not possible or not ideal, it becomes imperative that the pulmonary blood flow be restricted in order to allow the infant to thrive to an age where repair is feasible. The current approach for many of these children is to surgically limit their pulmonary blood flow. This can be accomplished by cinching down on the main or branch pulmonary arteries with a band (pulmonary artery band) or by completely removing the natural flow to the lungs and replacing it with a controlled source of blood flow through a Gortex shunt or surgical conduit. See published U.S. Application No. 2014/0236211 and U.S. Pat. No. 5,662,711 both incorporated herein by this reference.
Although effective in controlling pulmonary blood flow, the pulmonary artery band results in distortion of the pulmonary arteries which can negatively impact future surgical intervention. In addition, the pulmonary artery band can only be adjusted through additional surgery. Similarly, placement of a surgical shunt or conduit may result in distortion of the pulmonary arteries. Such artificial connections have the potential for thrombosis, distortion and occlusion, which may have fatal consequences. See also U.S. Pat. No. 6,638,257 and WO 2015/114471 both incorporated herein by this reference.